The present invention relates to housewares and, more particularly, to electric steam irons.
Electric steam irons emit steam from openings in a soleplate first to relax, and then to flatten, a fabric. In the past, it was widely believed that the more steam, and the more widely dispersed the distribution of the steam from the soleplate, the better the flattening effect. To this end, sole plates for steam irons have customarily been made with a large number of steam openings. In most cases, the openings have been distributed about the perimeter, as well as in the center of the sole plate. The belief that a large number of widely distributed steam openings was beneficial was so firmly held that at least one manufacturer of steam irons advertised that its steam irons had more openings than did those of the competition.
I have discovered that the above conventional practices are the result of serious misguidance as to the manner in which steam irons function.
It turns out that a steam is most effective for flattening a fabric when it is applied to the fabric at as cool a temperature as possible and then is completely vaporized by contact with, or proximity to, the hot surface of the soleplate before the sole plate leaves the area of the fabric infiltrated by the steam. Any steam that remains unvaporized when the soleplate moves away tends to increase rumpling or wrinkling of the fabric, rather than flatten the fabric.
I have discovered that the perimeter of a soleplate opening, even when it is well finished, acts as a cutting edge to produce lint from the fabric being ironed. Besides contributing to the wear of the fabric, such lint tends to enter the openings where it becomes charred over time by the high temperature to which it is exposed. Some steam irons experience an occasional expulsion of excess water through the steam openings. When charred lint is present in the soleplate, such excess water can deposit the brown charred lint onto the fabric, staining it. The more openings that exist in a soleplate, the greater is the total area of such openings. Accordingly, the greater the number of steam openings, the greater is the amount of lint produced, and the greater the tendency toward brown spotting.
The task of flattening fabric is made easier for the user when the iron passes over the fabric with minimum drag. Smoothness resulting from minimum drag is called glidability. A smooth finish on the surface of the soleplate improves glidability. However, I discovered that the number and orientation of steam openings also have an important effect on glidability. This effect appears to have been overlooked in the prior art.